This invention relates generally to a transducer fault detection system and, in particular, to a transducer fault detection apparatus and method for detecting anomalies in transducer output signals.
As is well known in the art, machinery protection systems are designed to accept a variety of transducer inputs and to monitor and display appropriate machinery parameters. Alarms are generated when conditions exceed user-established limits. These alarms can be used to automatically shut down the machine and/or to annunciate machinery problems to operators and other plant personnel. Additionally, these systems have incorporated monitoring features for minimizing the possibility of false alarms caused by, for example, a defective transducer, its associated interconnects and interconnect wiring, or transducer power supply.
One currently used detection scheme for censoring transducers is known as a xe2x80x9cNOT OKxe2x80x9d detection scheme which is accomplished by reading a transducer voltage signal and checking to see if it exceeds a predefined limit or goes outside a predefined voltage window having an upper and a lower limit or range. If the voltage signal exceeds the predefined limit or goes outside the predefined voltage window the signal is deemed not ok or anomalous and alarming off the transducer may be defeated thereby eliminating the possibility of false alarms caused by the transducer being defective, its associated interconnects and interconnect wiring being defective, or the transducer power supply being defective.
However, alarm conditions are missed any time anomalies in transducer output signals do not exceed the predefined limit or do not go outside the predefined window, Additionally, there is a lack of specificity on the root cause of transducer signals that are determined as xe2x80x9cNOT OKxe2x80x9d or anomalous.
Hence, there is a need for providing improved systems for censoring transducers for solve the problem of missing alarm conditions by missing anomalies in transducer output signals. Particularly, there is a need for solving the problem of missing alarm conditions by missing anomalies in transducer output signals that do exceed a predefined limit or do not go outside a predefined window. Additionally, there is a need for providing more specificity on the problem causing a xe2x80x9cNOT OKxe2x80x9d or anomalous transducer signal so that the causation of the problem can be quickly resolved and alarming off the transducer can be quickly restored if defeated.
The present invention is distinguished over the known prior art in a multiplicity of ways. In one aspect of the invention, a transducer fault detection system is provided that transforms transducer measurements into slew rate measurements, determines which, if any, of the slew rate measurements are anomalous or correlative to transducer faults, and generates alarms based on these determinations for annunciating faults to personnel and/or for defeating the transducer for eliminating the possibility of false alarms caused by faults such as transducer defects, transducer interconnect defects, transducer interconnect wiring defects, and/or transducer power supply defects. In particular, this aspect of the invention provides a transducer fault detection system that transforms transducer measurements into slew rate measurements, determines which, if any, of the slew rate measurements arc faster than that which could be due to a moving target being monitored by the transducer, and generates alarms based on whether or not any of the determined faster slew rate measurements are correlative to fault conditions.
Hence, a transducer fault detection system is provided that solves the problem of, inter alia, missing alarm conditions by missing anomalies in a transducer output signal such as that caused by an anomalous transducer output signal that does not exceed a predefined limit or that does not go outside a predefined window having an upper and a lower limit or range.
Additionally, the transducer fault detection system may correlate determined anomalous slew rate measurements to specific transducer faults so that the causation of the problem can be quickly resolved and alarming off the transducer can be quickly restored if defeated.
Furthermore, another aspect the invention provides a transducer fault detection system that transforms transducer signals or measurements into digitized voltage measurements and determines how long a succession of digitized voltage measurements remain within at least one defined voltage window or remain at, above, or below at least one defined voltage value for determining if there is a correlation between a measured time duration of digitized voltage measurements and a xe2x80x9cNot Okxe2x80x9d or anomalous condition. Each determined xe2x80x9cNot Okxe2x80x9d or anomalous condition can then be associated to a defined fault for gaining fault specificity on determined xe2x80x9cNot Okxe2x80x9d or anomalous transducer measurements so that the causation of the problem can be quickly resolved and alarming off the transducer can be quickly restored if defeated.
In one embodiment of the invention, a method for detecting faults from a transducer output signal includes the steps of: monitoring a slew rate of a transducer output signal; comparing the slew rate with a known value; correlating the slew rate to a fault when indicated by the comparison step.
In another embodiment of the invention, a transducer fault detection device comprises, in combination: at least one transducer outputting transducer measurements correlative to movement of a target of a mechanical system being monitored by said transducer; means, operatively coupled to the transducer, for transforming the transducer measurements into slew rate measurements; means for determining which, if any, of said slew rate measurements are faster than that which could be due to the moving target being monitored by said transducer; and means for ascertaining whether or not any of said determined faster slew rate measurements are correlative to transducer faults for providing fault detection.
In another embodiment of the invention, a method for detecting transducer faults includes the steps of transforming transducer measurements made by a transducer monitoring a moving target of a mechanical system into slew rate measurements; comparing the slew rate measurements to at least one previously known slew rate value which is known to be faster than that which could be due to the moving target of the mechanical system for determining which if any of the slew rate measurements are faster than the at least one previously known slew rate value, and correlating those slew rate measurements that are determined to be faster than the at least one previously known slew rate value to at least one transducer fault wherein each correlated slew rate measurement is characterized by having a faster slew rate than that which could be due to the moving target of the mechanical system.
In another embodiment of the invention, a method for detecting faults from a transducer output signal includes the steps of: transforming transducer signals into digitized voltage measurements; determining a time duration of how long a succession of the digitized voltage measurements remain within at least one defined voltage window; determining if the succession of the digitized voltage measurements remaining within at least the one defined voltage window for the determined time duration is correlative to an anomalous condition, and associating each determined anomalous condition to at least one defined fault for gaining fault specificity for providing mechanical system protection.
Moreover, having thus summarized the invention, it should be apparent that numerous modifications and adaptations may be resorted to without departing from the scope and fair meaning of the invention as set forth hereinbelow by the claims.